The present invention relates to syndiotactic polypropylene where on has been grafted a functional monomer. This product is of use as a compatibilizing agent, for example in blends of polyamide and of polypropylene or in blends of polypropylene and of glass fibres. The syndiotactic polypropylene is also of use as a coextrusion binder.
The coextrusion binder is composed (i) either of grafted syndiotactic polypropylene then optionally diluted in at least one polyolefin (C1) or in at least one polymer with an elastomeric nature (D) or in a blend of (C1) and (D), (ii) or of grafted isotactic polypropylene diluted in syndiotactic polypropylene and optionally in at least one polymer with an elastomeric nature (D).
These coextrusion binders are of use, for example, in the manufacture of multilayer materials for packaging. Mention may be made of materials comprising a film of polyamide (PA) and a film of polypropylene (PP), it being possible for the polypropylene film to be laminated onto the polyamide film or coextruded with the polyamide. The coextrusion binder is positioned between the polypropylene and the polyamide for good adhesion of the PA and of the PP. These multilayer materials can be three-layer structures PP/binder/EVOH in which EVOH denotes a copolymer of ethylene and of vinyl alcohol or a partially or completely ethylene/saponified vinyl acetate (EVA) copolymer or five-layer structures PP/binder/EVOH/binder/PP.